Electronic, wear-free safety engineering

WHEN the first PNOZ emergency stop safety relay was introduced by Pilz in 1987, it could not be foreseen that in a short space of time it would develop into an industry standard and its name become a synonym for safety relays.

Today, in Europe, this is beyond question and throughout the world the widespread usage of electromechanical safety relays for the monitoring of safety gates, light curtains and emergency stop devices is evidence of its reliability and practicality.

The application areas for this safety relay range from complex systems with a large number of safety devices, to machines with only one emergency stop function.

In practice, optimal operating conditions cannot always be expected. In turn, this places a high requirement on the performance of the safety relay.

The PNOZe1p is the first device in the new PNOZelog product family that covers all safety applications from category 2 up to and including category 4 as per EN 954-1 on an electronic basis for the first time.

It combines the advantages of the classic electromechanical PNOZ with those of modern electronics and in this way provides a high level of safety and availability of the plant.

PNOZelog is suitable for all safety applications from emergency stop switches, through the evaluation of floor mats and safety light barriers, all the way to the monitoring of safety gates.

The microprocessor technology used and the contact-less outputs provide for freedom from wear and maintenance, as well as long service life.

Developed on the basis of the experience gained in safe, integrated automation engineering, the product range has a special feature: the usage of safety-related (fail-safe) technology.

This means that, in accordance with category 4 as per AS 4024-1, two microprocessors with different hardware and software realisation perform the safety function.

The PNOZelog can also be connected to electronic proximity switches, semiconductor outputs on light barriers, reed contacts and also to the normal mechanical contacts on emergency stop switchgear and other safety-related sensors.

Here the low input currents make the device independent of voltage drop problems and at the same time enable wire cross-sections to be reduced without problems.

Test pulses propagating on these wires provide a high level of safety against shorts to earth, shorts across input terminals, and other short circuits.

The continual testing of the inputs for faults has also been implemented in the PNOZ elog range, so it is now possible to detect faults at an early stage.

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